A variety of different industries use extractors to extract and recover liquid substances entrained within solids. For example, producers of oil from renewable organic sources use extractors to extract oil from oleaginous matter, such as soybeans, rapeseed, sunflower seed, peanuts, cottonseed, palm kernels, and corn germ. The oleaginous matter is contacted with an organic solvent within the extractor, causing the oil to be extracted from a surrounding cellular structure into the organic solvent. As another example, extractors are used to recover asphalt from shingles and other petroleum-based waste materials. Typically, the petroleum-based material is ground into small particles and then passed through an extractor to extract the asphalt from the solid material into a surrounding organic solvent.
In higher volume processing facilities, operators use a continuous extractor to process a continuously flowing stream of material. The extractor includes a chamber in which solids material being processed and solvent are intermixed, allowing soluble components to be extracted from the solids material into the solvent. For example, an immersion extractor typically utilizes a pool of solvent through which solids material being processed is conveyed. The solvent and solids material may be conveyed in countercurrent directions through the immersion extractor, causing the concentration of extracted components in the solvent to increase from the solvent inlet to the solvent outlet while the concentration of the components in the solid material correspondingly decreases from the solids inlet to the solids outlet.
In practice, a conveyance system used to move solid material being processed through the extractor typically includes a conveyor driven by one or more drive shafts. The conveyor may also be connected to one or more idler shafts that rotate concurrent with but do not drive the conveyor. Each shaft of the conveyance system may be connected through a sidewall of the extractor and supported by a bearing assembly. The bearing assembly can constrain movement of the shaft relative to the sidewall of the extractor and also reduce friction between the shaft and the sidewall of the extractor during rotation.
Where shaft and bearing assembly are located below the liquid level of the extractor, the bearing assembly can be exposed to solvent, solid material being processed and other fouling material during operation. Over time, these materials have a tendency to degrade the bearing assembly, potentially necessitating costly and time consuming shutdown of the extractor. For example, if a submerged bearing assembly needs to be replaced, thousands of gallons of solvent may need to be evacuated from the extractor and placed in temporary storage to allow access to the bearing assembly for repair or replacement. Ensuring that an extractor bearing assembly provides reliable, long-term service can help ensure the safe and efficient operation of the extractor.